RESUMO
Insulin autoimmune syndrome is characterized by spontaneous hypoglycemia, high concentrations of serum immunoreactive insulin, and the presence of autoantibodies to insulin without previous insulin injection. A 71-year-old woman with diabetes, who had been treated with oral hypoglycemic agents, suffered from frequent hypoglycemia. High insulin levels and the presence of insulin autoantibodies were shown, so insulin autoimmune syndrome was diagnosed. Drugs containing sulfhydryl groups play an important role in the pathogenesis of insulin autoimmune syndrome. Alpha-lipoic acid, which contains a sulfhydryl group, was administered before the onset of hypoglycemia. The patient's human leukocyte antigen (HLA) type was HLA-Cw4 and DRB1*0406. There is a strong correlation between HLA-DRB1*0406 and insulin autoimmune syndrome. The patient was treated with prednisolone and has not had a hypoglycemic attack since. We report a case of insulin autoimmune syndrome, possibly associated with alpha-lipoic acid.